Ignition device



Dec. 17, 1946. E, H, SHANNON I 2,412,655

IGNITION DEVICE ELE... l..

` BY' Z Y Dec. 17, 194e. E H, SHANNON '2,412,655

IGNITION DEVICE Filed sept. so. 1944 2 sheets-sheet 2 INVENTOR EARL /zSHAA/NUA;

Patented Dec. 17,

TED STATE PATENT orrlca f 2,412,655 rourrrounnvrca Earl E. Shannon,Gary, Ind.

Application September 30, 1944, Serial No. 556,588

This invention relates to ignition devices and more particularly tothose whichv are operated electrically and used in connection with fuelburners.

It i's common practice to provide electrical ignition devices for fuelburners so as to maintain a continuous spark whereby temporary failuresin the fuel supply system will not cause explosions upon resumption ofthe fuel supply after such failures. An ignition device for such purposeis shown in the patent to Miess No. 2,318,408. dated May 4, 1943. Suchan ignition device as shown therein consists generally of alongitudinally extending burner having a single electrode spark plugarranged in an opening intermediate the length thereof to which currentis supplied from a suitable source of power. There is connected to theinner end of the center electrode of the spark plug, an elongatedelectrode which extends substantially perpendicular thereto and isarranged axially of the burner.y n the other end of the burner there isarranged a grounded electrode at which point the spark is produced foryigniting the gases issuing forth from the outer end of the burner.

A similar ignition device is shown in my co pending application, SerialNo. 518,269, led Jan uary 14. 1944, and entitled Spark plug.

- In `oth of the above devices the ground electrode is arranged outsideof the burner in the furnace, the elongated electrode extending throughthe burner to a point adjacent the ground electrode, thus forming aspark gap. Thus the electrodes are exposed to the heat of the furnaceand in a relatively short time must be replaced. This is especially trueof the ground electrode which has no means for adjustment. The burneralso makes considerable noise when operating, which I have found is dueto the dis position of the ground electrode in the fuel stream.

It is an object of my'invention to provide an ignition device forburners in which the electrodes are protected from the heat of thefurnace.

Another object is to provide an arrangement of electrodes in a tubularburner so that the noise or howl or the burner is mui'ied.

These and other objects will be more apparent after referring to thefollowing specification and attached drawings, in which:

Figure 1 is a sectional view through the burner;

Figure 2 is an end view thereof; and

Figure 3 is a general arrangement of the and tube assembly.

Referring more particularly to the drawings burner 2 Claims. (Cl.175-115) the numeral 2 designates a metallic fuel feed tube having theusual inlet end 2a and outlet end 2b, the latter of which is adapted toextend Within the`furnace or the radiant tube assembly with which thedevice of the invention is to operate. At the inlet end '2a of the fuelfeed tube 2 there is provided the usual means 3 for' supplying gastogether with an air inlet d.

In the side wall of the fuel feed tube 2 there is a screw-threadedaperture 5 which is adapted to receive the externally screw-threadedhousing 6 of a conventional spark plug from which the ground electrodehas been removed. Within the spark plug housing 6 vthere is disposed inscrewthreaded engagement therewith the spark plug sleeve l which isadapted to' hold in rigid rela-l tionship therein the porcelaininsulator 8 of the spark plug, the center electrode l B extendingtherethrough and well'into the center of the fuel The extended end ofthe center electrode d is screw-threaded and carries thereon aninternally screw-threaded sleeve l@ which has a cross-aperture l2therein. This cross-aperture l2 receives an elongated electrode i3 whichprojectsvfrom the exit end 2b of the fuel feed tube 2. The exit end 2bof the fuel feed tube 2 is pro-f vided with a refractory cap |41 havinga series of apertures it therein, one of which is centrally disposed toreceive the extended end of the electrode IB, which does not passcompletely through the cap lf3. This refractory cap lil is suitablyretained in the end of the fuel feed tube 2 by means of a screw-threadedretainer cap i6 which is threaded to the end of the extension sleeve il,this sleeve being provided with a ground electrode i8 similar to thatof'a conventional spark plug. If desired the electrode IB can befastened directly to the burner -body and the sleeve ll omitted.

Immediately opposite the screw-threaded aperture E in the fuel feed tube2 is a similar aperture i9 in which there is disposed a screw-threadedplug 20. By. removing the screw-threaded plug 2d and loosening theexternally-threaded sleeve l of the spark plug the porcelain insulatormay be rotated to rellevethe set-screw eect of the electrode 9 withrespect to the electrode i3 whereby the latter may be suitably adjusted.After the desired adjustment the porcelain insulator d may be rotated toagain obtain the set-screw effect of the electrode 9 with respect to theelectrode i3 and the externally-threaded sleeve 1 drawn tight tomaintain the adjustment.

From the foregoing it will be seen there is provided 'a spark gapdirectly in the pathof the atmetel xuel stream wherein electrodes I3 andI8 defining said spark gap are disposed entirely within the burner insuch a manner as to be removed from intimatecontact with the flame andprotected from the heat of the furnace tube. By virtue of the describedarrangement the electrodes do not deteriorate from use and as a resultthe required spark gap is constantly unvariably maintained providingefllcient ignition of the combustible gases with minimum adjustment andmaintenance.

Referring to Figure 3 which shows a typical burner installation in whicha radiant tube as sembly 22 is fastened to and passes through the wall24 of a furnace, attention is directed to the striking similarity inshape and contour of the tube assembly 22 to a tone chamber of anordinary musical instrument. In this instance the fuel emitting from theburner produces audible noise which is increased by the myriad minuteexplosions occurring during combustion.

In prior art practice it is customary to provide a spark gap forignition purposes on the outside of the burner directly in the exitingfuel stream, and in such arrangements the grounded electrode forms anobstruction which disturbs the equilibrium of the fuel stream andcreates additional noise.

The complexity of noises so created, and substantially amplified by thetone chamber, cannot be properly identified with known musical tones andpossesses no acoustic characteristic except that of obnoxiousness. Thevolume of noise as well as its tonal quality is also effected by thepressure applied to the burner, the location of the burner, and othervariables too numerous to mention.

By relocating the grounded y electrode I8 as shown in Figure 1 withinthe burner, it has been found that objectionable noises formerly presenthave practically disappeared, or at least have been altered in pitch orvibration frequency so as to Ibe no longer audible. This phenomenon maybe partially accounted for by the fact that the combustible mixture isalready in a turbulent 45 state within the discharge end of tube 2caused rby the haine effect of refractory cap I4 which obstructssomewhat the flow 'of the mixture. It has been pointed out that theprimary audible noises occurring outside of the burner are caused toincrease in magnitude by the ground electrode located in the samevicinity, but by relocating the electrode within the yburner andadjacent the refractory cap I4 as shown, there -is no noise creatingeffect on the fuel stream.

While I have shown and described one specific embodiment of myinvention, it will be under.

stood that 'I do not wish to be limited exactly thereto since variousmodifications may be made within the scope of my invention, as definedby the following claims.

I claim:

l. In an ignition device for use with a tubular burner having a.perforated refractory cap on itsv discharge end, the combination whichincludes an electrode disposed within and extending longitudinally ofthe burner, said electrode being supported by and terminating in saidrefractory cap, a ground electrode disposed within the l'burner andlocated within two inches of said reits discharge end, the combinationwhich includes EARL H. SHANNON.

